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<FONT color="green">001</FONT>    /*<a name="line.1"></a>
<FONT color="green">002</FONT>     * Copyright (C) 2008-2012, fluid Operations AG<a name="line.2"></a>
<FONT color="green">003</FONT>     *<a name="line.3"></a>
<FONT color="green">004</FONT>     * FedX is free software: you can redistribute it and/or modify<a name="line.4"></a>
<FONT color="green">005</FONT>     * it under the terms of the GNU Affero General Public License as<a name="line.5"></a>
<FONT color="green">006</FONT>     * published by the Free Software Foundation, either version 3 of the<a name="line.6"></a>
<FONT color="green">007</FONT>     * License, or (at your option) any later version.<a name="line.7"></a>
<FONT color="green">008</FONT>     * <a name="line.8"></a>
<FONT color="green">009</FONT>     * This program is distributed in the hope that it will be useful,<a name="line.9"></a>
<FONT color="green">010</FONT>     * but WITHOUT ANY WARRANTY; without even the implied warranty of<a name="line.10"></a>
<FONT color="green">011</FONT>     * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the<a name="line.11"></a>
<FONT color="green">012</FONT>     * GNU Affero General Public License for more details.<a name="line.12"></a>
<FONT color="green">013</FONT>     * <a name="line.13"></a>
<FONT color="green">014</FONT>     * You should have received a copy of the GNU Affero General Public License<a name="line.14"></a>
<FONT color="green">015</FONT>     * along with this program.  If not, see &lt;http://www.gnu.org/licenses/&gt;.<a name="line.15"></a>
<FONT color="green">016</FONT>     */<a name="line.16"></a>
<FONT color="green">017</FONT>    <a name="line.17"></a>
<FONT color="green">018</FONT>    package com.fluidops.fedx.optimizer;<a name="line.18"></a>
<FONT color="green">019</FONT>    <a name="line.19"></a>
<FONT color="green">020</FONT>    import java.util.ArrayList;<a name="line.20"></a>
<FONT color="green">021</FONT>    import java.util.LinkedList;<a name="line.21"></a>
<FONT color="green">022</FONT>    import java.util.List;<a name="line.22"></a>
<FONT color="green">023</FONT>    <a name="line.23"></a>
<FONT color="green">024</FONT>    import org.apache.log4j.Logger;<a name="line.24"></a>
<FONT color="green">025</FONT>    import org.openrdf.query.algebra.QueryModelNode;<a name="line.25"></a>
<FONT color="green">026</FONT>    import org.openrdf.query.algebra.Service;<a name="line.26"></a>
<FONT color="green">027</FONT>    import org.openrdf.query.algebra.StatementPattern;<a name="line.27"></a>
<FONT color="green">028</FONT>    import org.openrdf.query.algebra.TupleExpr;<a name="line.28"></a>
<FONT color="green">029</FONT>    import org.openrdf.query.algebra.helpers.QueryModelVisitorBase;<a name="line.29"></a>
<FONT color="green">030</FONT>    <a name="line.30"></a>
<FONT color="green">031</FONT>    import com.fluidops.fedx.algebra.EmptyNJoin;<a name="line.31"></a>
<FONT color="green">032</FONT>    import com.fluidops.fedx.algebra.EmptyResult;<a name="line.32"></a>
<FONT color="green">033</FONT>    import com.fluidops.fedx.algebra.ExclusiveGroup;<a name="line.33"></a>
<FONT color="green">034</FONT>    import com.fluidops.fedx.algebra.ExclusiveStatement;<a name="line.34"></a>
<FONT color="green">035</FONT>    import com.fluidops.fedx.algebra.NJoin;<a name="line.35"></a>
<FONT color="green">036</FONT>    import com.fluidops.fedx.algebra.TrueStatementPattern;<a name="line.36"></a>
<FONT color="green">037</FONT>    import com.fluidops.fedx.exception.OptimizationException;<a name="line.37"></a>
<FONT color="green">038</FONT>    import com.fluidops.fedx.structures.QueryInfo;<a name="line.38"></a>
<FONT color="green">039</FONT>    import com.fluidops.fedx.util.QueryStringUtil;<a name="line.39"></a>
<FONT color="green">040</FONT>    <a name="line.40"></a>
<FONT color="green">041</FONT>    <a name="line.41"></a>
<FONT color="green">042</FONT>    /**<a name="line.42"></a>
<FONT color="green">043</FONT>     * Optimizer with the following tasks:<a name="line.43"></a>
<FONT color="green">044</FONT>     * <a name="line.44"></a>
<FONT color="green">045</FONT>     * 1. Group {@link ExclusiveStatement} into {@link ExclusiveGroup}<a name="line.45"></a>
<FONT color="green">046</FONT>     * 2. Adjust the join order using {@link JoinOrderOptimizer}<a name="line.46"></a>
<FONT color="green">047</FONT>     * <a name="line.47"></a>
<FONT color="green">048</FONT>     * <a name="line.48"></a>
<FONT color="green">049</FONT>     * @author as<a name="line.49"></a>
<FONT color="green">050</FONT>     */<a name="line.50"></a>
<FONT color="green">051</FONT>    public class StatementGroupOptimizer extends QueryModelVisitorBase&lt;OptimizationException&gt; implements FedXOptimizer {<a name="line.51"></a>
<FONT color="green">052</FONT>    <a name="line.52"></a>
<FONT color="green">053</FONT>            public static Logger log = Logger.getLogger(StatementGroupOptimizer.class);<a name="line.53"></a>
<FONT color="green">054</FONT>            <a name="line.54"></a>
<FONT color="green">055</FONT>            protected final QueryInfo queryInfo;<a name="line.55"></a>
<FONT color="green">056</FONT>                    <a name="line.56"></a>
<FONT color="green">057</FONT>            public StatementGroupOptimizer(QueryInfo queryInfo) {<a name="line.57"></a>
<FONT color="green">058</FONT>                    super();<a name="line.58"></a>
<FONT color="green">059</FONT>                    this.queryInfo = queryInfo;<a name="line.59"></a>
<FONT color="green">060</FONT>            }<a name="line.60"></a>
<FONT color="green">061</FONT>    <a name="line.61"></a>
<FONT color="green">062</FONT>    <a name="line.62"></a>
<FONT color="green">063</FONT>    <a name="line.63"></a>
<FONT color="green">064</FONT>            @Override<a name="line.64"></a>
<FONT color="green">065</FONT>            public void optimize(TupleExpr tupleExpr) {<a name="line.65"></a>
<FONT color="green">066</FONT>                    tupleExpr.visit(this);<a name="line.66"></a>
<FONT color="green">067</FONT>            }<a name="line.67"></a>
<FONT color="green">068</FONT>    <a name="line.68"></a>
<FONT color="green">069</FONT>            @Override<a name="line.69"></a>
<FONT color="green">070</FONT>            public void meet(Service tupleExpr) {<a name="line.70"></a>
<FONT color="green">071</FONT>                    // stop traversal<a name="line.71"></a>
<FONT color="green">072</FONT>            }<a name="line.72"></a>
<FONT color="green">073</FONT>            <a name="line.73"></a>
<FONT color="green">074</FONT>            <a name="line.74"></a>
<FONT color="green">075</FONT>            @Override<a name="line.75"></a>
<FONT color="green">076</FONT>            public void meetOther(QueryModelNode node) {<a name="line.76"></a>
<FONT color="green">077</FONT>                    if (node instanceof NJoin) {<a name="line.77"></a>
<FONT color="green">078</FONT>                            super.meetOther(node);          // depth first<a name="line.78"></a>
<FONT color="green">079</FONT>                            meetNJoin((NJoin) node);<a name="line.79"></a>
<FONT color="green">080</FONT>                    } else {<a name="line.80"></a>
<FONT color="green">081</FONT>                            super.meetOther(node);<a name="line.81"></a>
<FONT color="green">082</FONT>                    }<a name="line.82"></a>
<FONT color="green">083</FONT>            }<a name="line.83"></a>
<FONT color="green">084</FONT>    <a name="line.84"></a>
<FONT color="green">085</FONT>            <a name="line.85"></a>
<FONT color="green">086</FONT>            protected void meetNJoin(NJoin node) {<a name="line.86"></a>
<FONT color="green">087</FONT>                    <a name="line.87"></a>
<FONT color="green">088</FONT>                    LinkedList&lt;TupleExpr&gt; newArgs = new LinkedList&lt;TupleExpr&gt;();<a name="line.88"></a>
<FONT color="green">089</FONT>                    <a name="line.89"></a>
<FONT color="green">090</FONT>                    LinkedList&lt;TupleExpr&gt; argsCopy = new LinkedList&lt;TupleExpr&gt;(node.getArgs());<a name="line.90"></a>
<FONT color="green">091</FONT>                    while (!argsCopy.isEmpty()) {<a name="line.91"></a>
<FONT color="green">092</FONT>                            <a name="line.92"></a>
<FONT color="green">093</FONT>                            TupleExpr t = argsCopy.removeFirst();<a name="line.93"></a>
<FONT color="green">094</FONT>                            <a name="line.94"></a>
<FONT color="green">095</FONT>                            /*<a name="line.95"></a>
<FONT color="green">096</FONT>                             * If one of the join arguments cannot produce results,<a name="line.96"></a>
<FONT color="green">097</FONT>                             * the whole join expression does not produce results.<a name="line.97"></a>
<FONT color="green">098</FONT>                             * =&gt; replace with empty join and return<a name="line.98"></a>
<FONT color="green">099</FONT>                             */<a name="line.99"></a>
<FONT color="green">100</FONT>                            if (t instanceof EmptyResult) {                         <a name="line.100"></a>
<FONT color="green">101</FONT>                                    node.replaceWith( new EmptyNJoin(node, queryInfo));<a name="line.101"></a>
<FONT color="green">102</FONT>                                    return;<a name="line.102"></a>
<FONT color="green">103</FONT>                            }<a name="line.103"></a>
<FONT color="green">104</FONT>                            <a name="line.104"></a>
<FONT color="green">105</FONT>                            /*<a name="line.105"></a>
<FONT color="green">106</FONT>                             * for exclusive statements find those belonging to the <a name="line.106"></a>
<FONT color="green">107</FONT>                             * same source (if any) and form exclusive group<a name="line.107"></a>
<FONT color="green">108</FONT>                             */<a name="line.108"></a>
<FONT color="green">109</FONT>                            else if (t instanceof ExclusiveStatement) {<a name="line.109"></a>
<FONT color="green">110</FONT>                                    ExclusiveStatement current = (ExclusiveStatement)t;<a name="line.110"></a>
<FONT color="green">111</FONT>                                    <a name="line.111"></a>
<FONT color="green">112</FONT>                                    List&lt;ExclusiveStatement&gt; l = null;<a name="line.112"></a>
<FONT color="green">113</FONT>                                    for (TupleExpr te : argsCopy) {         <a name="line.113"></a>
<FONT color="green">114</FONT>                                            /* in the remaining join args find exclusive statements<a name="line.114"></a>
<FONT color="green">115</FONT>                                             * having the same source, and add to a list which is<a name="line.115"></a>
<FONT color="green">116</FONT>                                             * later used to form an exclusive group<a name="line.116"></a>
<FONT color="green">117</FONT>                                             */<a name="line.117"></a>
<FONT color="green">118</FONT>                                            if (te instanceof ExclusiveStatement) {<a name="line.118"></a>
<FONT color="green">119</FONT>                                                    ExclusiveStatement check = (ExclusiveStatement)te;<a name="line.119"></a>
<FONT color="green">120</FONT>                                                    if (check.getOwner().equals(current.getOwner())) {<a name="line.120"></a>
<FONT color="green">121</FONT>                                                            if (l==null) {<a name="line.121"></a>
<FONT color="green">122</FONT>                                                                    l = new ArrayList&lt;ExclusiveStatement&gt;();<a name="line.122"></a>
<FONT color="green">123</FONT>                                                                    l.add(current);<a name="line.123"></a>
<FONT color="green">124</FONT>                                                            }<a name="line.124"></a>
<FONT color="green">125</FONT>                                                            l.add(check);<a name="line.125"></a>
<FONT color="green">126</FONT>                                                    }                                                       <a name="line.126"></a>
<FONT color="green">127</FONT>                                            }                                               <a name="line.127"></a>
<FONT color="green">128</FONT>                                    }<a name="line.128"></a>
<FONT color="green">129</FONT>                                    <a name="line.129"></a>
<FONT color="green">130</FONT>                                    <a name="line.130"></a>
<FONT color="green">131</FONT>                                    // check if we can construct a group, otherwise add directly<a name="line.131"></a>
<FONT color="green">132</FONT>                                    if (l!=null) {<a name="line.132"></a>
<FONT color="green">133</FONT>                                            argsCopy.removeAll(l);<a name="line.133"></a>
<FONT color="green">134</FONT>                                            newArgs.add( new ExclusiveGroup(l, current.getOwner(), queryInfo ));<a name="line.134"></a>
<FONT color="green">135</FONT>                                    } else {<a name="line.135"></a>
<FONT color="green">136</FONT>                                            newArgs.add( current );<a name="line.136"></a>
<FONT color="green">137</FONT>                                    }<a name="line.137"></a>
<FONT color="green">138</FONT>                            }<a name="line.138"></a>
<FONT color="green">139</FONT>                            <a name="line.139"></a>
<FONT color="green">140</FONT>                            /*<a name="line.140"></a>
<FONT color="green">141</FONT>                             * statement yields true in any case, not needed for join<a name="line.141"></a>
<FONT color="green">142</FONT>                             */<a name="line.142"></a>
<FONT color="green">143</FONT>                            else if (t instanceof TrueStatementPattern) {<a name="line.143"></a>
<FONT color="green">144</FONT>                                    if (log.isDebugEnabled())<a name="line.144"></a>
<FONT color="green">145</FONT>                                            log.debug("Statement " + QueryStringUtil.toString((StatementPattern)t) + " yields results for at least one provided source, prune it.");<a name="line.145"></a>
<FONT color="green">146</FONT>                            }<a name="line.146"></a>
<FONT color="green">147</FONT>                            <a name="line.147"></a>
<FONT color="green">148</FONT>                            else<a name="line.148"></a>
<FONT color="green">149</FONT>                                    newArgs.add(t);<a name="line.149"></a>
<FONT color="green">150</FONT>                    }<a name="line.150"></a>
<FONT color="green">151</FONT>                    <a name="line.151"></a>
<FONT color="green">152</FONT>                    // if the join args could be reduced to just one, e.g. OwnedGroup<a name="line.152"></a>
<FONT color="green">153</FONT>                    // we can safely replace the join node<a name="line.153"></a>
<FONT color="green">154</FONT>                    if (newArgs.size()==1) {<a name="line.154"></a>
<FONT color="green">155</FONT>                            log.debug("Join arguments could be reduced to a single argument, replacing join node.");<a name="line.155"></a>
<FONT color="green">156</FONT>                            node.replaceWith( newArgs.get(0) );<a name="line.156"></a>
<FONT color="green">157</FONT>                            return;<a name="line.157"></a>
<FONT color="green">158</FONT>                    }<a name="line.158"></a>
<FONT color="green">159</FONT>                    <a name="line.159"></a>
<FONT color="green">160</FONT>                    // in rare cases the join args can be reduced to 0, e.g. if all statements are <a name="line.160"></a>
<FONT color="green">161</FONT>                    // TrueStatementPatterns. We can safely replace the join node in such case<a name="line.161"></a>
<FONT color="green">162</FONT>                    if (newArgs.size()==0) {<a name="line.162"></a>
<FONT color="green">163</FONT>                            log.debug("Join could be pruned as all join statements evaluate to true, replacing join with true node.");<a name="line.163"></a>
<FONT color="green">164</FONT>                            node.replaceWith( new TrueStatementPattern( new StatementPattern()));<a name="line.164"></a>
<FONT color="green">165</FONT>                            return;<a name="line.165"></a>
<FONT color="green">166</FONT>                    }<a name="line.166"></a>
<FONT color="green">167</FONT>                    <a name="line.167"></a>
<FONT color="green">168</FONT>                    List&lt;TupleExpr&gt; optimized = newArgs;<a name="line.168"></a>
<FONT color="green">169</FONT>                    <a name="line.169"></a>
<FONT color="green">170</FONT>                    // optimize the join order<a name="line.170"></a>
<FONT color="green">171</FONT>                    optimized = JoinOrderOptimizer.optimizeJoinOrder(optimized);<a name="line.171"></a>
<FONT color="green">172</FONT>    <a name="line.172"></a>
<FONT color="green">173</FONT>                    // exchange the node<a name="line.173"></a>
<FONT color="green">174</FONT>                    NJoin newNode = new NJoin(optimized, queryInfo);<a name="line.174"></a>
<FONT color="green">175</FONT>                    node.replaceWith(newNode);<a name="line.175"></a>
<FONT color="green">176</FONT>            }       <a name="line.176"></a>
<FONT color="green">177</FONT>            <a name="line.177"></a>
<FONT color="green">178</FONT>    }<a name="line.178"></a>




























































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